Contents

vnop_exchange_args

Call down to a filesystem or device to check if a file is ready for I/O and request later notification if it is not currently ready.

Declaration

struct vnop_exchange_args {
    ...
};

Discussion

In general, regular are always "ready for I/O" and their select vnops simply return "1." Devices, though, may or may not be read; they keep track of who is selecting on them and send notifications when they become ready. xnu provides structures and routines for tracking threads waiting for I/O and waking up those threads: see selrecord(), selthreadclear(), seltrue(), selwait(), selwakeup(), and the selinfo structure (sys/select.h).

Topics

Fields

Instance Properties

See Also

vnode